Frictional Behaviors of Polyurethane Ionomers Under Water Lubrication

Polyurethane as a high-performance polymer material characterized by high toughness, corrosion resistance, and good wear resistance can be widely used in bearing applications. However, under water-lubricated conditions, the inherently weak hydrophilicity of polyurethane surfaces limits the formation of a stable hydrated lubrication layer, thereby restricting their tribological performance. To overcome this limitation, sulfonate groups-containing polyurethane ionomers were synthesized via condensation polymerization, endowing the material surface with a negative charge. Specifically, the sulfonic acid group can adsorb hydrated cations through electrostatic action to form a hydrated lubrication film on the surface, which can effectively improve the material's tribological performance. The friction coefficients of polyurethane ionomer with TBAB-BES molar ratio of 3% (PUI-3) were significantly reduced when a 3 wt% NaCl solution was used as the lubricant. When the sliding speed was 0.01 m/s, the coefficient of friction for PUI-3 was 0.053, achieving a 60% reduction in friction coefficient. Furthermore, the PUI-3 with SO 3 − exhibited both excellent mechanical properties and water resistance. This work provides a new approach to improving the tribological properties of polyurethane materials in marine environments.